1. Field of the Invention
The invention is in the field of recorders utilizing pyrographic and thermo-chemical processes.
2. Description of the Prior Art
Strip chart recorders have traditionally employed a strip of chart paper moving past an ink pen. The position of the pen on the paper corresponds to the value of data being graphed on the chart paper. The ink pen and the mechanism positioning the pen on the chart paper provide an analog display of the data, and mechanical parts required for an analog presentation such as this inherently present calibration and accuracy problems and have a susceptibility to vibration or shock.
There are also chart recording systems in which paper having a dielectric coating is passed over a stationary recording head which includes etched styluses. The styluses are pulsed selectively by digital circuitry forming a series of dots on the coded paper. Systems such as this are expensive and often require further processing of the paper after the action of the styluses thereon.
Thermal printers wherein heat-sensitive paper is marked by heat-generating elements acting on the paper have been used for printing out digits, letters of the alphabet, etc. These devices have been utilized to replace traditional typewriters at computer terminals and in other functions requiring rapid printing of characters. Examples of this type of device may be found in U.S. Pat. Nos. 3,163,489 to Borne et al., 3,139,026 to Mechstroth et al., 3,596,055 to Elston, 3,501,615 to Merryman et al., 3,340,381 to Best, 3,496,333 to Alexander et al., 3,515,850 to Cady, 3,161,457 to Schroeder et al., 3,495,070 to Zissen, 3,312,979 to Torre et al., 3,409,902 to Merryman, and 3,578,946 to Colello.